Note: Future work is planned here to make it possible to list python
attributes on a module without loading the module by inspecting ASTs or
bytecode, but currently any iteration of PythonModule objects insists they
must be loaded, and will use inspect.getmodule.

Returns

a generator yielding PythonAttribute instances describing the attributes
of this module.

any type of exception. Importing modules is a risky business; the
erorrs of any code run at module scope may be raised from here, as well as
ImportError if something bizarre happened to the system path between the
discovery of this PythonModule object and the attempt to import it. If you
specify a default, the error will be swallowed entirely, and not
logged.